USB: whiteheat: Added bounds checking for bulk command response

This patch fixes a potential security issue in the whiteheat USB driver
which might allow a local attacker to cause kernel memory corrpution. This
is due to an unchecked memcpy into a fixed size buffer (of 64 bytes). On
EHCI and XHCI busses it's possible to craft responses greater than 64
bytes leading a buffer overflow.

Change-Id: I373cd63c720dbe2a17c7c778f87b3855038143c8
Signed-off-by: James Forshaw <forshaw@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/serial/whiteheat.c b/drivers/usb/serial/whiteheat.c
index 36a7740e827c997ebbc156bfcb6e908cb02d1804..cc5a430dc357cb276cd46dff9c7977b0d02f3a4b 100644 (file)
--- a/drivers/usb/serial/whiteheat.c
+++ b/drivers/usb/serial/whiteheat.c
@@ -521,6 +521,10 @@ static void command_port_read_callback(struct urb *urb)
                dev_dbg(&urb->dev->dev, "%s - command_info is NULL, exiting.\n", __func__);
                return;
        }
+       if (!urb->actual_length) {
+               dev_dbg(&urb->dev->dev, "%s - empty response, exiting.\n", __func__);
+               return;
+       }
        if (status) {
                dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n", __func__, status);
                if (status != -ENOENT)
@@ -541,7 +545,8 @@ static void command_port_read_callback(struct urb *urb)
                /* These are unsolicited reports from the firmware, hence no
                   waiting command to wakeup */
                dev_dbg(&urb->dev->dev, "%s - event received\n", __func__);
-       } else if (data[0] == WHITEHEAT_GET_DTR_RTS) {
+       } else if ((data[0] == WHITEHEAT_GET_DTR_RTS) &&
+               (urb->actual_length - 1 <= sizeof(command_info->result_buffer))) {
                memcpy(command_info->result_buffer, &data[1],
                                                urb->actual_length - 1);
                command_info->command_finished = WHITEHEAT_CMD_COMPLETE;